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Publication numberUS5128397 A
Publication typeGrant
Application numberUS 07/697,837
Publication dateJul 7, 1992
Filing dateMay 9, 1991
Priority dateMay 9, 1991
Fee statusLapsed
Also published asCA2068116A1, DE69202919D1, DE69202919T2, EP0512955A1, EP0512955B1
Publication number07697837, 697837, US 5128397 A, US 5128397A, US-A-5128397, US5128397 A, US5128397A
InventorsDouglas W. Horsey, Ambelal R. Patel
Original AssigneeCiba-Geigy Corporation
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Stabilized ethylene-vinyl acetate copolymer hot melt adhesive systems
US 5128397 A
Abstract
Hot melt adhesive compositions stabilized against thermal degradation, discoloration, skin formation and substantial viscosity changes, said adhesives being based on ethylene-vinyl acetate copolymer and a hydrocarbon tackifying resin and containing a stabilizer system of a hindered phenol antioxidant, a phosphite costabilizer and an acid scavenger.
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Claims(29)
What is claimed is:
1. A stabilized hot melt adhesive composition comprising
(a) ethylene-vinyl acetate copolymer;
(b) an effective tackifying amount of a hydrocarbon tackifying resin; and
(c) an effective stabilizing amount of a stabilizer composition comprising
(1) a phenolic antioxidant;
(2) a phosphite co-stabilizer; and
(3) an acid scavenger selected from the group consisting of epoxidized oils, alkali metal salts of higher fatty acids, alkaline earth metal salts of higher fatty acids and amines.
2. The composition of claim 1, wherein said hydrocarbon tackifying resin is selected from the group consisting of aliphatic petroleum hydrocarbon resins and hydrogenated derivatives thereof, aromatic petroleum hydrocarbon resins and hydrogenated derivatives thereof and alicyclic petroleum hydrocarbon resins and hydrogenated derivatives thereof, polyterpene hydrocarbon resins and hydrogenated derivatives thereof, and mixtures thereof.
3. The composition of claim 2, wherein said hydrocarbon tackifying resin is hydrogenated.
4. The composition of claim 1, wherein components (a) and (b) are present in a weight ratio of 10:90 to 90:10.
5. The composition of claim 4, wherein components (a) and (b) are present in a weight ratio of 25:75 to 75:25.
6. The composition of claim 1, which additionally contains (d) up to 50%, by weight of components (a) and (b), of a petroleum derived wax.
7. The composition of clain 6, wherein components (a), (b) and (d) are present in a weight ratio of 1:1:1.
8. The composition of claim 1, wherein said hindered phenolic antioxidant corresponds to the formula
R1 X--(Ca H2a)-Q                            (I)
wherein R1 is a group of the formula Ia, ##STR18## X is oxygen or sulfur, a is an integer from 6 to 30, be is an integer from 0 to 6, R2 and R3 are independently C1- C18 alkyl, C5- C12 cycloalkyl, phenyl or C7- C9 aralkyl, and R2 is also hydrogen, Q is hydrogen or --A--(Cy H2y)--R4, A is oxygen, sulfur or ##STR19## y is an integer from 2 tro 20, B is C1- C4 alkyl or C1- C4 alkanoyl, and R4 is hydrogen, hydroxy, C1- C4 alkanoyloxy or a group of the formula Ib, ##STR20## wherein R2, R3 and b are as defined above, r is 1, d is an integer from 2 to 6, and Q1 is a divalent aliphatic hydrocarbon of 1 to 18 carbon atoms, a divalent aromatic or aromatic aliphatic hydrocarbon of 6 to 20 carbon atoms or a group of the formula IIa when r is also 0 ##STR21## wherein f is an integer from 1 to 4; ##STR22## wherein R2, R3 and b are as defined above, and Q2 is C1- C18 alkylene;
R1 X--[(Cz H2z)--Y]e --R5         (IV)
wherein R1 and X are as defined above, z is an integer from 2 to 6, e is an integer from 3 to 40, Y is oxygen or sulfur, and R5 is hydrogen, C1- C4 alkyl or a group of the formula Ia; ##STR23## wherein R6 and R7 are independently C1- C18 alkyl, C5- C12 cycloalkyl, phenyl or C7- C9 aralkyl, and R6 is also hydrogen, and A1 is a group >C(R8)R9 wherein R8 and R9 are independently hydrogen or C1- C6 alkyl; ##STR24## wherein R3 is defined above, p is 1 or 2 and Q3 is C2- C10 alkylene; or ##STR25## wherein R10 is C1- C10 alkykl or C5- C12 cycloalkyl,
R11 independently is C1- C18 alkyl, phenyl or benzyl and
R12 is hydrogen or methyl.
9. The composition of claim 1, wherein the hindered phenolic antioxiant corresponds to forumla I and X is oxygen, b is an interger from 0 to 2, R2 and R3 are alkyl of 1 to 8 carbon atoms, A is oxygen, y is 2 and R4 is hydrogen or a group of the formula Ia.
10. The composition of claim 9, wherein the hindered phenolic antioxidant is octadecyl 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate or 2-ethylhexyl-3-(3'-5'-di-tert.butyl-4-hydroxyphenyl)propionate.
11. The composition of claim 8, wherein the hindered phenolic antioxidant corresponds to formula II and r is 1, R2 and R3 are C1- C8 alkyl, b is 2, d is 2 or 4 and Q1 is C2- C10 alkylene or pentaerythritol.
12. The composition of claim 11, wherein the hindered phenolic antioxidant is 1,6-hexamethylene bis[3'-5'-di-tert-butyl-4'-hydroxyhydrocinnamate] or tetrakis[methylene 3-(3'-5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane.
13. The composition of claim 8, wherein the hindered phenolic antioxidant corresponds to formula II, r is 0 and Q1 is formula IIa.
14. The composition of claim 8, wherein the hindered phenolic antioxidant corresponds to formula III and R2 and R3 are C1- C8 alkyl, b is 2 and Q2 is C2-`C 6 alkylene.
15. The composition of claim 8, wherein the hindered phenolic antioxidant corresponds to formula IV and X and Y are oxygen, b is 0-2, R2 and R3 are C1- C8 alkyl, z is 2, e is 3-20 and R5 is a group of formula Ia.
16. The composition of claim 8, whererin the hindered phenolic antioxidant corresponds to formula VI and R6 and R7 are methyl or tert.butyl and R8 and R9 are hydrogen or methyl.
17. The composition of claim 8, wherein the hindered phenolic antioxidant corresponds to formula VIII and R10 is C1- C4 alkyl, R11 is C8- C12 alkyl and R13 is hydrogen.
18. The composition of claim 1, wherein said phosphite co-stabilizer corresponds to the formulae ##STR26## wherein R14 is tert.butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl, and one of
R15 and R16 is hydrogen and the other is hydrogen, methyl, tert.butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl; ##STR27## wherein R17 is n-C18 H37, ##STR28## R18, R19 and R20 independently are C1- C18 alkyl, R20 is also hydrogen and
R19 is also D--COOR21 wherein D is a direct bond, methylene or ethylene and R21 is C1- C18 alkyl; or ##STR29##
19. The composition of claim 18, wherein the phosphite corresponds to formula IX and is tris(2,4-di-tert.butylphenyl)phosphite.
20. The composition of claim 18, wherein the phosphite corresponds to formula X.
21. The composition of claim 18, wherein the phosphite corresponds to formula XI.
22. The composition of claim 1, wherein said acid scavenger is epoxidized soy bean oil, epoxidized castor oil, epoxidized linseed oil or epoxidize sunflower oil.
23. The composition of claim 1, wherein said acid scavenger is calcium stearate.
24. The composition of claim 1, wherein the relative concentration of components (c)(1),(c) (2) and (c)(3) are 25 to 74%, 5 to 74% and 2to 50%, by weight of component (c).
25. The composition of claim 24, wherein said relative concentrations are 47.5%, 47.5% and 5%, by weight of component (c).
26. The composition of claim 1, wherein component (c) is present in a concentration of 0.1-2.5%, by weight of the total adhesive composition.
27. The composition of claim 1, wherein said hindered phenolic antioxidant is selected from the group consisting of tetrakis[methylene-3-(3'-5'-di-tert.butyl-4'-hydroxyphenyl)-propionate]methane, thiodiethylene bis(3,5-di-tert.butyl-4-hydroxy)hydrocinnamate, octadecyl3-(3',5'-di-tert.butyl-4'-hydroxyphenyl)propionate, triethylene glycol bis-[3-(3'-tert.butyl-5'-methyl-4'-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris-(3',5'-di-tert.butyl-4'-hydroxybenzyl)benzene,2,6-di-tert. butyl-p-cresol, tris(3,5-di-tert.butyl-4-hydroxybenzyl)isocyanurate,1,6-hexamethylene bis(3,5-di-tert.butyl-4-hydroxy-hydrocinnamate, and 2,4-bis(n-octylthiomethyl)-6-methylphenol; said phosphite co-stabilizer is selected from the group consisting of tris(2,4-di-tert.butylphenyl)phosphite, bis(2,4-di-tert.butylphenyl)pentaerythritol diphosphite, and tris(4-nonylphenyl)phosphite; and said acid scavenger is epoxidized soy bean oil or calcium stearate.
28. The composition of claim 1, which additionally contains (e) a (mixed alkylated) diphenylamine antioxidant.
29. A method for stabilizing a hot melt adhesive composition comprising an ethylene-vinyl acetate copolymer and an effective tackifying amount of a hydrocarbon tackifying resin against oxidative and thermal degradation which comprises incorporating into said hot melt adhesive composition an effective oxidative and thermal stabilizing amount of (1) a phenolic antioxidant, (2) a phosphite co-stabilizer and (3) an acid scavenger selected from the group consisting of epoxidized oils, alkali metal salts of higher fatty acids and alkaline earth metal salts of higher fatty acids and amines.
Description

Hot melt adhesives, including those based on ethylene vinyl acetate copolymer, are especially susceptible to oxidation due to high temperature (180 C.) compounding, storage, handling and application. As the performance requirements for such adhesives increased, the use of antioxidants evolved to prevent discoloration, undesirable viscosity changes and skin formation on the surface of the adhesive. Hindered phenols were the primary antioxidant of choice fo stabilization of the adhesive systems.

A further approach to achieving stabilization beyond that provided by the hindered phenols involved the use of secondary antioxidants such as thiosynergists or phosphite stabilizers including triarylphosphites. The combination of primary and secondary antioxidants provided stabilization performance beyond that which could be expected based on the sum of the performance of the individual components.

A complication was, however, encountered by the frequent use of white or light colored hydrocarbon tackifying resins in adhesive formulations where good color stability is required. Thus, negative interactions were experienced with such hydrocarbon tackifiers as evidenced by way of gray-black discoloration upon heating. Since it was hypothesized that the interactions involved the phosphite costabilizer, the applicability of the latter has been substantially reduced. Accordingly, solutions to this problem are required which eliminate the discoloration effect while still preserving the effective properties provided by the presence of the tackifier and the phosphite costabilizer.

Background material on these issues are provided by the following: U.S. Pat. No. 4,360,617 which discloses blends of phenols and symmetrical triarylphosphites for stabilizing a broad range of organic polymers including elastomers and ethylene-vinyl acetate copolymers; U.S. Pat. No. 3,658,743 which discloses synergistic combinations of phenols, an organic sulfide or thioester and an epoxide or phosphite ester for the stabilization of hydrocarbon elastomers; U.S. Pat. No. 4,835,200 which discloses stabilizer systems of a thio compound, a phenolic antioxidant, a tris(nonylated phenyl)phosphite and an aliphatic compatible epoxy compound for use in various tackified block copolymer resin systems; and U.S. Pat. No. 4,857,572 which discloses (alkylthioalky)phenols with optional addition of phosphites for use in stabilizing various elastomers.

It has now been surprisingly discovered that a unique combination of primary and secondary antioxidants and of an acid scavenger substantially eliminates the aforementioned difficulties encountered in the stabilization of ethylene-vinyl acetate hot melt adhesives containing hydrocarbon tackifying resins. Thus, the blend of hindered phenol, phosphite and acid scavenger provides color stability while minimizing viscosity changes, heat degradation and skin formation. By facilitating the use of phosphite costabilizers, the combination provides stabilization properties which additionally exceed the performance of the individual state of the art antioxidants.

The primary components of the hot melt adhesive system are ethylene-vinyl acetate copolymer, a hydrocarbon tackifying resin and, optionally, petroleum derived waxes and various plasticizing oils.

The applicable tackifying resins may be described as hydrogenated and non-hydrogenated aliphatic petroleum hydrocarbon resins (preferably hydrogenated varieties) resulting from the polymerization of monomers consisting primarily of mono- and diolefins, hydrogenated and non-hydrogenated aromatic petroleum hydrocarbon resins and hydrogenated and non-hydrogenated alicyclic petroleum hydrocarbon resins. Additionally, hydrogenated and non-hydrogenated polyterpene hydrocarbon resins may be used as the tackifying resin. Mixtures of the above are also applicable. Such tackifying resins will be present in concentrations ranging from 10 to 90%, by weight, and preferably 25 to 50%, by weight. The particular resin will be selected on the basis of compatibility with the adhesive system, with colorless or white tackifiers being particularly preferred. ARKON P-90 from Arakawa Chemical, ESCOREZ 5300 from Exxon Chemical and REGALREZ 1094 from Hercules are typical commercial tackifying resins.

The petroleum derived waxes are optionally present in concentrations ranging from 0 to 50%, by weight, and serve to impart greater fluidity to the molten material, flexibility to the set adhesive and wetting characteristics. Paraffin and microcrystalline waxes with melting points of 55-110 C. as well as polyethylene or Fischer-Tropsch waxes are illustrative of this component.

Plasticizing or extending oils may also be present in order to provide wetting action and viscosity control. Concentrations up to 50%, by weight, are applicable. Typical oils include olefin oligomers, vegetable and animal oils and naphthenic oils.

The combination of stabilizers which substantially eliminates heat degradation, color formation, undesirable viscosity changes and skin formation comprise

(a) a hindered phenolic antioxidant;

(b) a phosphite co-stabilizer; and

(c) an acid scavenger.

Hindered phenols are well known to those skilled in the art and correspond to the formulae

R1 X--(Ca H2a)--Q                           (I)

wherein R1 is a group of the formula Ia, ##STR1##

X is oxygen or sulfur, a is an integer from 6 to 30, preferably 6 to 18, b is an integer from 0 to 6, R2 and R3 are independently C1 -C18 alkyl, C5 -C12 cycloalkyl, phenyl or C7 -C9 aralkyl, and R2 is also hydrogen, Q is hydrogen or --A--(Cy H2y)--R4, A is oxygen, sulfur or ##STR2## y is an integer from 2 to 20,

B is C1 -C4 alkyl or C1 -C4 alkanoyl, and R4 is hydrogen, hydroxy, C1 -C4 alkanoyloxy or a group of the formula Ib, ##STR3## wherein R2, R3 and b are as defined above, r is 1, d is an integer from 2 to 6, and Q1 is a divalent aliphatic hydrocarbon of 1 to 18 carbon atoms, a divalent aromatic or aromatic aliphatic hydrocarbon of 6 to 20 carbon atoms or a group of the formula IIa when r is also O ##STR4## wherein f is an integer from 1 to 4; ##STR5## wherein R2, R3 and b are as defined above, and Q2 is C1 -C18 alkylene; ##STR6## wherein R1 and X are as defined above, z is an integer from 2 to 6, e is an integer from 3 to 40, preferably 3 to 10, Y is oxygen or sulfur, and R5 is hydrogen, C1 -C4 alkyl or a group of the formula Ia; ##STR7## wherein R6 and R7 are independently C1 -C18 alkyl, C5 -C12 cycloalkyl, phenyl or C7 -C9 aralkyl, and R6 is also hydrogen, and A1 is a group >C(R8)R9 wherein R8 and R9 are independently hydrogen or C1 -C6 alkyl; ##STR8## wherein R3 is as defined above, p is 1 or 2 and Q3 is C2 -C10 alkylene; and ##STR9## wherein R10 is C1 -C10 alkyl or C5 -C12 cycloalkyl,

R11 independently is C1 -C18 alkyl, phenyl or benzyl and

R12 is hydrogen or methyl.

Alkyl is for example methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 1,1,3,3-tetramethylbutyl, nonyl, decyl, undecyl, dodecyl or octadecyl.

C1 -C18 alkyloxy is for example methoxy, ethoxy, propoxy, n-butoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy or octadecyloxy.

C1 -C4 alkanoyl is for example acetyl, propionyl or butyryl.

C1 -C4 alkanoyloxy is for example acetyloxy, propionyloxy or butyryloxy.

C5 -C12 cycloalkyl is for example cyclopentyl, cyclohexyl or cyclooctyl. Cyclohexyl is preferred.

C7 -C9 aralkyl is in particular C7 -C9 phenylalkyl, for example benzyl, α-methylbenzyl, α,α-dimethylbenzyl or phenylethyl. Benzyl is preferred.

C1 -C18 alkylene is for example methylene, dimethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene or octadecamethylene.

For compounds of formula II when r is 1, Q1 is a bivalent hydrocarbon can be e.g. straight-chain or branched C2 -C10 alkylene or C2 -C6 alkylidene such as, for example, ethylene, ethylidene, trimethylene, tetramethylene, pentamethylene, 2,2-dimethylpropane-1,3-diyl, hexamethylene, heptamethylene, octamethylene, decamethylene, 2,2-pentamethylene-propane-1,3-diyl, and cyclohexylene or C6 -C10 arylene such as, for example, phenylene, phenylene substituted by one or more C1 -C4 alkyl, or naphthylene.

Q1 as a trivalent, tetravalent or pentavalent hydrocarbon can be e.g. a group of the following formulae ##STR10## alkanetriyl of 3 to 6 carbon atoms, such as e.g. glyceryl or trimethylylpropane or alkanetetrayl of 4 to 6 carbon atoms such as e.g. pentaerythrityl.

Formula Ia represents preferably one of the following groups: ##STR11##

Formula Ib is in particular one of the groups ##STR12##

In the group of the formula IIa when r is O, f is preferably 1 or 2.

Those compositions are preferred, wherein component (a) is a compound of the formula I, II, III, IV, V or VI, in particular I, II, III or IV.

Z is preferably a direct bond or C1 -C6 alkylene.

Compounds of formula I which are preferred exhibit X as oxygen, b as an integer from 0 to 2, R2 and R3 as alkyl of 1 to 8 carbon atoms, A as oxygen, y as 2, R4 as hydrogen or a group of the formula Ia. Particularly preferred are those compounds wherein R2 and R3 are tert-butyl positioned ortho to the hydroxyl group and b is 2. Compounds of preference are octadecyl 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate and 2-ethylhexyl 3-(3',5', -di-tert.butyl-4-hydroxyphenyl)propionate.

Compounds of formula II which are preferred exhibit R2 and R3 as C1 -C8 alkyl, in particular tert-butyl positioned ortho to the hydroxyl group, b as 2, d as 2 or 4 and Q1 as C2 -C10 alkylene or pentaerythritol. Specific compounds of preference are 1,6-hexamethylene bis[3',5'-di-tert-butyl-4'-hydroxyhydrocinnamate] and tetrakis[methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. A preferred compound of formula II when Q1 is formula IIa is tris(3,5-di-tert.butyl-4-hydroxybenzyl)isocyanurate.

Compounds of formula III which are preferred exhibit R2 and R3 as C1 -C8 alkyl and preferably tert-butyl positioned ortho to the hydroxyl group, b as 2 and Q2 as C2 -C6 alkylene. The specific compound of preference is N,N'-hexamethylene bis[3,5-di-tert-butyl-4-hydroxyhydrocinnamide].

Compounds of formula IV which are preferred exhibit X and Y as oxygen, b as an integer from 0 to 2, R2 and R3 as alkyl of 1 to 8 carbon atoms, z as 2, e as an integer from 3 to 20, and R5 as a group of the formula Ia. Particularly preferred are those compounds wherein R2 and R3 are tert-butyl positioned ortho to the hydroxyl group. A specific compound of preference is triethylene glycol bis[3-(3'-tert-butyl-5'-methyl-4'-hydroxyphenyl)-propionate].

Compounds of formula VI which are preferred exhibit R6 and R7 as methyl or tert-butyl and R8 and R9 as hydrogen or methyl. Specific compounds of preference are bis[2-hydroxy-3-tert-butyl-5-methylphenyl]methane and 1,1-bis[2'-hydroxy-3',5'-di-tert-butylphenyl]ethane.

A preferred compound of formula VII is ##STR13##

A preferred compound of formula VIII has R10 as C1 -C4 alkyl and most preferably methyl, R11 as C8 -C12 alkyl and most preferably n-octyl, and R13 as hydrogen.

Applicable phosphites correspond to the formulae ##STR14## wherein R14 is tert.butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl, and one of

R15 and R196 is hydrogen and the other is hydrogen, methyl, tert.butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl; ##STR15## wherein R17 is n-C18 H37, ##STR16## R18, R19 and R20 independently are C1 -C18 alkyl, R20 is also hydrogen and

R19 is also D-COOR21 wherein D is a direct bond, methylene or ethylene and R21 is C1 -C18 alkyl and ##STR17##

A preferred compound of formula IZ is tris(2,4-di-tert.butylphenyl)phosphite. A preferred compound of formula XI is bis(2,4di-tert.butylphenyl)pentaarythitol diphosphite.

Applicable acid scavengers incolude epoxidized oils and alkali metal and alkaline earth metal salts of higher fatty acids. The epoxidized oil is readily miscible in the adhesive formation. Typical oils include epoxidized soy bean oil, epoxidized caster oil, epoxidized linseed oil and epoxidized sunflower oil. Typical salts include calcium stearate, zinc stearate, magnesium stearate, sodium ricinoleate, potassium palmitate, antimony pyrocatecholate or tin pyrocatecholate. Amines are also applicable including alkanolamines such as triethanolamine and sterically hindered amines such as bis-(2,2,6,6-tetramethylpiperidyl)-sebacate, bis-(1,2,2,6,6-pentamethylpiperidyl)-sebacate, n-butyl-3,5-di-tert.butyl-4-hydroxybenzyl malonic acid, bis-(1,2,2,6,6-pentamethylpiperidyl)ester, condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, condensation product of N,N'-(2,2,6,6-tetramethylpiperidyl)-hexamethylenediamine and 4-tert.octylamino-2,6-dichloro-1,3,5-s-triazine, tris-(2,2,6,6-tetramethylpiperidyl)-nitrolotriacetate, tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarbonic acid and 1,1,'-(1,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone).

The concentrations (by weight) of the respective components in the stabilizer system are as follows: from about 25 to 74% of hindered phenol: and preferably 47.5%; from 5 to 74% of phosphite co-stabilizer, and preferably 25 to 74% and most preferably 47.5%; and from about 2 to 50% of acid scavenger, preferably 2 to 10% and most preferably 5%. The total amount of stabilizer system added to the adhesive component is from about 0.1-2.5%, by weight of total adhesive formulation, and preferably 0.5-1.0%.

Additional stabilizers may be optionally incorporated into the adhesive compositions. Such additives include other antioxidants, light stabilizers and the like. Blends including mixed alkylated diphenylamine antioxidants are particularly preferred. Typical alkyl groups include C4 -C18 alkyls.

The adhesive compositions of the present invention are typically prepared by blending the components at an elevated temperature, preferably between about 130 C. and about 200 C., until a homogeneous blend is obtained, usually less than three (3) hours. Various methods of blending are known to the art and any method that produces a homogeneous blend is satisfactory. The resultant adhesives may then preferably be used in a wide variety of product assembly applications.

The following examples illustrate the preferred embodiments of the invention. In these examples, all parts and percentages given are by weight unless otherwise noted.

The following materials are employed in these examples:

"Adhesive"-1:1:1 weight ratio of ethylene-vinyl acetate copolymer (ELVAX 250 from DuPont): hydrogenated hydrocarbon tackifier (ARKON P-90 from Arakawa Chemical): microcrystalline wax (Bareco BE Square 195 from Petrolite).

A. tetrakis[methylene 3-(3',5'-di-tert.butyl-4'-hydroxyphenyl)propionate]methane

B. thiodiethylene bis(3,5di-tert.butyl-4hydroxy)hydrocinnamate

C. octadecyl 3-(3',5'-di-tert.butyl-4'-hydroxyphenyl)propionate

D. triethylene glycol bis[3-(3'-tert.butyl-5'-methyl-4'-hydroxyphenyl)propionate]

E. 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert.butyl-4'-hydroxybenzyl)benzene

F. 2,6-di-tert.butyl-p-cresol

G. tris(3,5-di-tert.butyl-4-hydroxybenzyl) isocyanurate

H. 1,6-hexamethylene bis(3,5-di-tert.butyl-4-hydroxy-htdrocinnamate

I. 2,4-bis(n-octylthiomethyl)-6-methylphenol

J. tris(2,4-di-tert.butylphenyl)phosphite

K. bis(2,4-di-tert.butylphenyl)pentaerythritol diphosphite

L. tris(4-nonylphenyl)phosphite

M. epoxidized soy bean oil (Drapex 6.8 from Witco Chemical)

N. epoxidized soy bean oil (Flexol from Union Carbide)

P. (alkylated mixture)diphenylamine

Q. calcium stearate

EXAMPLE 1

This Example illustrates the adverse effects of phosphites on ethylene-vinyl acetate hot melt systems containing hydrogenated hydrocarbon tacktifiers.

The adhesive composition ("Adhesive") and additives are blended until homogeneous. Samples are then maintained in an oven at 177 C. and measured for color at periodic intervals utilizing a Gardner Color Scale.

Additionally, melt viscosity of the sample is determined using a Brookfied Viscometer (spindle #21, 177 C.) and comparing the 177 C. melt viscosity after 96 hours oven aging to the initial melt viscosity.

The following results are obtained.

______________________________________            Gardner Color at 177 C.Additive  Conc. (%)    0     24    48  96 hrs______________________________________--        --           0     6     11  13A         0.5          0     3     5    8A         1.0          0     3     4    7A/J (1:1) 0.5          0     2     4   11A/J (1:1) 1.0          0     3     B   BA/K (1:1) 1.0          0     2     4   10A/L (1:1) 0.5          0     G     B   BA/L (1:1) 1.0          0     G     B   BA/J (1:1)*     1.0          0     G     G   B______________________________________ *contains hydrogenated hydrocarbon tackifier (ESCOREZ 5300 from Exxon) G -- gray coloration B -- black coloration
EXAMPLE 2

This Example illustrates the improved performance characteristics provided by the compositions of this invention.

The following data is generated using the procedure of Example 1.

______________________________________       Gardner ColorAdditive  Conc. %    0     24  48   72   96______________________________________                                      % Δ Melt                                      Visc.                                      at 96 hrs.I.A      0.5        1     2   3    5    6    +5A      1.0        1     2   3    4    6    +15A/J    0.5/0.5    1     3   G    --   --   +21A/J/M  0.5/0.5/0.05             1     1   2    3    4    +12A/J/N  0.5/0.5/0.05             1     2   2    3    4    +12II.A/J    0.5/0.5    1     3   G    --   --   +18A/J/M  .495/.495/.01             1     2   5    G    --   +12A/J/M  .49/.49/.02             1     2   3    4    5    +10A/J/M  .485/.485/.03             1     2   3    3    4    +8A/J/M  .48/.48/.04             1     2   3    3    4    +5A/J/M  .475/.475/.05             1     2   3    3    4    +3III.A/J/M  .475/.475/.05             1     2   3    4    5    +25A/J/M  .356/.356/.038             1     2   3    4    5    +25A/J/M  .238/.238/.024             1     2   3    5    7    +25IV.*--     --         0     8   9    11   12   --A      1.0        0     2   5    6    7    --A/J    0.5/0.5    0     3   G    --   --   --A/J/M  .475/.475/.05             0     1   2    2    3    --A/J/M  .49/.49/.02             0     0   1    2    3    --V.                                      120 hrs.--     --         0     7   10   11   12   13A      0.5        0     3   3    4    4    6A      1.0        0     3   3    4    4    6A/M    .5/.025    0     3   3    4    4    6A/Q    .5/.025    0     3   4    7    7    8J      0.5        0     2   G    G    G    GJ/M    .5/.025    0     2   6    10   11   12J/Q    .5/.025    0     3   6    9    11   12A/J    .5/.5      0     4   8    B    B    BA/J/M  .5/.5/.05  0     1   1    2    3    5A/J/Q  .5/.5/.05  0     1   1    3    4    5______________________________________ *Escorez 5300 tackifier
EXAMPLE 3

The procedures of Example 1 are repeated with a series of additional hindered phenols.

______________________________________        Gardner ColorAdditive   Conc. (%)  0       24  48    72   96______________________________________--      --         0       6   9     11   12J       1.0        0       G   B     --   --A       1.0        0       3   5     5    5A/J     0.5/0.5    0       4   B     --   --A/J/M   .475/.475/.05              0       3   3     4    6B       1.0        0       4   5     10   11B/J     0.5/0.5    0       G   B     --   --B/J/M   .475/.475/.05              0       3   3     4    6C       10         0       4   5     5    6C/J     0.5/0.5    0       5   B     --   --C/J/M   .475/.475/.05              0       3   4     4    4D       1.0        0       5   6     7    7D/J     0.5/0.5    0       G   B     --   --D/J/M   .475/.475/.05              0       3   5     6    6E       1.0        0       6   6     7    7E/J     0.5/0.5    0       G   B     --   --E/J/M   .475/.475/.05              0       3   4     5    6F       1.0        0       6   9     10   10F/J     0.5/0.5    0       4   B     --   --F/J/M   .475/.475/.05              0       3   3     4    6G       1.0        0       5   6     7    7G/J     0.5/0.5    0       G   B     --   --G/J/M   .475/.475/.05              0       3   3     3    4H       1.0        0       4   6     6    7H/J     0.5/0.5    0       G   B     --   --H/J/M   .475/.475/.05              0       2   3     3    4I       1.0        0       4   6     10   12I/J     0.5/0.5    0       G   B     --   --I/J/M   .475/.475/.05              0       3   6     11   11P/A     0.5/0.5    0       4   5     6    7P/A/J   .25/.25/.5 0       5   B     --   --P/A/J/M 24/.24/.47/.05              0       1   2     3    4______________________________________

The data in Examples 2 and 3 clearly illustrates the significantly improved stabilization characteristics provided to the ethylene-vinyl acetate hot melt adhesive formulations.

Summarizing, it is seen that this invention provide improved stabilization systems for use in ethylene-vinyl acetate hot melt adhesive compositions containing hydrogenated hydrocarbon tackifying resins. Variations may be made in procedures, proportions and materials without departing from the scope of the invention as defined by the follwoing claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3658743 *Apr 30, 1970Apr 25, 1972Alfred E SidwellStabilization of unsaturated hydrocarbon elastomers by synergistic combination of a phenolic compound an organic sulfide or thioester and an epoxide or phosphite ester
US4360617 *Feb 23, 1981Nov 23, 1982Ciba-Geigy CorporationStabilizer systems of triarylphosphites and phenols
US4835200 *Dec 19, 1986May 30, 1989Shell Oil CompanyColor stable hot melt adhesive
US4857572 *Feb 10, 1988Aug 15, 1989Ciba-Geigy CorporationElastomers and tackifier resins
US4994508 *Jul 14, 1988Feb 19, 1991Asahi Kasei Kogyo Kabushiki KaishaSpecific hydrogenated block copolymer composition and process for producing the same
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5276258 *Dec 2, 1992Jan 4, 1994Ciba-Geigy CorporationAnd tackifier resins, phenolic compounds containing thioether groups and epoxidized fatty acids or esters
US5541246 *Oct 24, 1994Jul 30, 1996Arizona Chemical CompanyPapermaking
US6984680 *Apr 12, 2004Jan 10, 2006Adherent Laboratories, Inc.used as a pick-up labeling adhesive composition that uses synthetic hydrocarbon tackifying resins that are low in odor, light in color, and hypoallergenic to obtain good adhesive properties combined with improved user safety and comfort.
US7323239Oct 22, 2002Jan 29, 2008Exxonmobil Chemical Patents Inc.Multilayer, peelable; adhering layer blend of ethylene-vinyl acetate copolymer and resin having a softening point above 40 degrees C. coextruded with ethylene or propylene polymer backing; tensile strength and stiffness at minimum thickness; protects automobiles during transportation and storage.
US7331533Mar 22, 2004Feb 19, 2008Compositech, L.L.C.making metallic concentrate from metallic ore and for making plastic articles from the tailings therefrom; froth flotation
US7452933 *Dec 8, 2006Nov 18, 2008Lg Chem, Ltd.Cross-linked polyethylene having excellent inhibition of sweat-out and insulation properties
US7495048Oct 8, 2003Feb 24, 2009Exxonmobil Chemical Patents Inc.Heat sealable compositions and uses thereof
WO1999041065A1 *Aug 3, 1998Aug 19, 1999Demer CorpThermoplastic articles made from recycled products and process for making
Classifications
U.S. Classification524/290, 524/133, 524/153, 524/289, 524/343, 524/114, 524/151, 524/101, 524/564, 524/488, 524/128, 524/400, 524/62, 524/330, 524/349
International ClassificationC09J123/08, C09J131/04, C08K5/00
Cooperative ClassificationC08K5/005, C09J123/08
European ClassificationC08K5/00P6, C09J123/08
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